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The Dismantling and Decommissioning (D&D) of nuclear facilities poses several challenges for radioactivity measurement laboratories involved in environmental radiation monitoring plans. One of them is the definition of the detection limits to be achieved for the radionuclides analysis in different samples. The detection limits should be set in such a way that the obtained concentration values for each radionuclide are easily discriminated from certain maximum activity concentration levels. These maximum activity concentration levels are usually set in view of the respective dose contributions from each radionuclide. There are some national legislations that settle detection limits for drinking water. However, there is no regulation containing detection limits for groundwater or surface water. In this way, different institutions or companies require very different detection limits for radioactivity concentration assessment in those types of water associated with D&D activities. In this work, we focus on the detection limits required for the D&D activities in rainwater, surface water and groundwater. We propose detection limits obtained by applying the WHO methodology for maximum activity concentration levels and compare with those requested by radioactive waste management agencies and regulatory bodies. Some real cases where our proposal allows identification of events are analysed and conclusions are extracted. [ABSTRACT FROM AUTHOR]

In the context of the INSIDER European project, the suitability of existing methodologies for in-situ measurements under constraint environments in nuclear facilities following a decommissioning and dismantling (D&D) process was analysed. Firstly, an analysis of the different methodologies for in-situ measurements was made along with a study of the different types of constrained environments that could appear in the D&D process as well as their expected level of impact on the measurement methodologies. Based on this analysis, a decision-helping tool for the selection of the suitable in-situ equipment/detector to be used in nuclear facilities for the different phases in any D&D process has been developed, depending on the constrained environment. This tool is named INSPECT, acronym for In-Situ Probe SelECtion Tool. The software is therefore potentially of use to those working in radiological characterization with in-situ instrumentation in any radiological or nuclear D&D process. [ABSTRACT FROM AUTHOR]

Today, the measurement of 14C in environmental samples is of particular interest, as it enables the assessment of the impact caused by nuclear activities and the fossil fuel industry on the environment. In order to assure the quality of 14C measurement results, the strategy to enlarge the validation of three radioanalytical methods in environmental samples using liquid scintillation spectrometry—the direct counting of water, bubbling of water and combustion of solids—is presented. Due certain difficulties, such as the lack of quality control materials and the scarcity of proficiency test and intercomparison exercises, especially in solid samples, a set of water and soil samples were prepared for the purpose by tracing them with known quantities of a 14C standard solution at two activity levels. Aliquots were subjected to the corresponding method and their activity concentration was calculated. Finally, uncertainty, detection limit, accuracy, precision, repeatability and linearity were analysed. The acceptance criteria for the quality parameters were previously established according to ISO 13528:2015 standard and Eurachem Laboratory Guide to Method Validation. In all the methods, the studied parameters fall within the acceptance range, so they are validated. The quality of the results in real samples is controlled through field validation. [ABSTRACT FROM AUTHOR]

In this work, two Tc radiochemical isolation methods—a conventional method by Triskem TEVA® resin and a rapid method by Empore™ Tc Rad Disk—are compared in the field of nuclear decommissioning and 99Tc assessment. The conventional method results more selective than the rapid one, being able to remove almost 100% of the main radiological interferers with the exception of the 90Y; however, the rapid method obtains higher chemical yields (97% vs. 80%) and slightly lower detection limits (0.025 Bq vs. 0.030 Bq) than the conventional. Both methods are similar with regards to equipment and reagent costs. [ABSTRACT FROM AUTHOR]

The aim of this paper is to statistically characterize gross beta activity concentrations in ground-level air in Bilbao (northern Spain) by analysing five years (2014–2018) worth of weekly measurements in aerosols collected in filters to analyse the impact of local meteorological parameters on concentrations. In addition, synoptic meteorological scenarios associated with anomalous beta surface activity concentrations were identified. Over this five-year period, beta activity concentrations ranged from 35.45 µBq/m3 to 1778 µBq/m3 with a mean of 520.12 ± 281.77 µBq/m3. A positive correlation was found with the alpha concentrations (0.67), with an average of 0.138 for the alpha/beta ratio, and a low correlation was found with 7Be (0.16). Statistical analysis identified a seasonal component in the time series, increasing, on average, beta activity concentrations from winter to autumn. The highest beta activity concentrations were measured under the arrival of southerly land winds with low wind speeds, while the wind analysis (surface winds and air masses) of two different seasonal periods (autumn 2015 and winter 2017) have highlighted how small variations in synoptic and local winds highly influence beta activity concentrations. These results are relevant to understand the meteorological factors affecting beta activity concentrations in this area and hence to define meteorological scenarios that are in favour to high/anomalous surface activity concentrations that are harmful to the environmental and public health. [ABSTRACT FROM AUTHOR]